In my world, there exists a race of amphibians we'll call "phrogs". Phrogs were a relatively peaceful race, who evolved a kind of telepathy to allow them to communicate underwater, which got increasingly sophisticated until they developed full blown dream sharing. They were spirited from their home planet and genetically engineered to be soldiers. These new world phrogs fall into two categories: Suns, the footsoldiers of the big bads cosmic empire, and the Moons, a smaller caste of dream raiders, who's function ranges from gathering intel to essentially DDOSing a victim's mind. I'm focused on the Suns for this question.
Like amphibians/salamanders on Earth, phrogs on their homeworld undergo a metamorphosis, where they transition from being fully aquatic to being amphibious, surviving on land and in water. Only... they did on their homeworld. As a means of control, their captors have bred away the gland which produces a hormone that allows them to metamorphosise. If left untreated, a phrog soldier, whilst otherwise growing to be fully sized, will remain wholly aquatic its entire life, and when on land, must wear an elaborate "wetsuit" in order to breathe.
My worry here is this; we know that axolotls in the real world, who experience this same kind of neoteny, are relatively weaklimbed compared to a metamorphosised salamander. While this all sounds cool conceptually, what advantage has an aquatic animal got over a terrestrial one in combat on land? If any?